A team of Canadian scientists has used geology-style drill cores from an Ontario lake bottom to gather evidence of toolmaking and perhaps even duckhunting by ancient aboriginals about 10,000 years ago -the first discovery of its kind in North America, and one that could point the way to further breakthroughs in underwater archeology around the world.

Led by researcher Lisa Sonnenburg of McMaster University in Hamilton, Ont., the team took sediment samples from a shallow section of Rice Lake -a popular summer vacation spot northeast of Toronto -where prehistoric First Nations were known to have camped soon after the glaciers retreated at the end of the last ice age.

The scientists found more than 150 tiny flakes of quartz in the lake's murky depths -strong evidence that an ancient shoreline, submerged long ago, was used by some of Canada's earliest inhabitants as a site for manufacturing spear points, scrapers and other tools for fishing and hunting.

The discovery not only sheds new light on the activities of those prehistoric people, but also pioneers a novel method of detecting the presence of ancient aboriginals in what are now drowned landscapes -a technique with huge research potential in Canada's Great Lakes region and many other places around the world where suspected settlement sites have became inundated over time.

The team's analysis of telltale markings of human activity on the quartz fragments -known as "microdebitage" among archeologists -shows that the technique "offers a reliable quantitative method for narrowing search areas and for identifying new areas of underwater archeological potential," the researchers conclude in a study published in the July issue of the journal Geology.

Sonnenburg said the team targeted "what we thought was an old shoreline" and that the drill cores proved that's "exactly what it was."

She recalled "staring down the barrel of a microscope" for a long time before beginning to see quartz chips at a consistent layer of sediment, about two metres deep, that suggested the ancient occupation of the site.

"I hyperventilated a little bit," she said of the discovery.

While looking for larger artifacts in a submerged landscape amounts to searching "for a needle in a haystack," Sonnenburg said using the coring technique to find evidence of toolmaking could be useful at many potential archeological sites -especially in the Great Lakes area, where shifting shorelines have flooded many potential archeological sites since humans first began occupying the continent more than 10,000 years ago.

The discovery of now-submerged archeological sites is expected to provide breakthroughs in the coming years for researchers trying to trace the initial peopling of the Americas via Pacific coastal routes in present-day Alaska, British Columbia, Washington, Oregon and California.